Lesson (1) Chemistry and measurement

When we look around ourselves, we see the vast complicated world God had created for us . Since human was created, he has been trying to work out the secrets of universe and create methods to control it. So many scholars, scientists and philosophers did their best to know what universe is all about. These laborious efforts resulted in the formation of facts, principles, concepts, laws and theories which describe knowledge. These things are included in a system called "science"

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Science: The systematic building which organizes knowledge in the form of facts, principles, concepts, scientific theories and an organized way of search.

Each branch of science is concerned with the study of certain phenomena, one of these branches is "Chemistry"

Chemistry: The science that studies the structure and properties of matter , changes that occur to it, reaction of substances with each other and the suitable conditions for it.

Chemistry is one of the oldest physical sciences ancient civilizations had used in all fields of life (Medicine, pharmacy, glass industry, clothes dyeing…etc). Ancient Egyptians used it in Mummification process.

1- The study of the atomic and molecular structures of substances and how they bond.

2- The description of the chemical properties of substances.

3- The discovery of how substances perform their roles.

4- Chemical reactions by which reactants change into products.

5- The discovery of methods to control the conditions of the reaction; in order to create new products that serve medicine, pharmacy, industry and agriculture.

6- Solving some environmental problems (water pollution, soil pollution, air pollution, lack of water and energy resources…etc)

Chemistry plays an important role in other sciences

Chemistry and Biology:-

Biology: The science that studies living organisms

Chemistry helps in understanding the chemical reactions occurring within living organisms

Biochemistry: The science that studies the chemical structure of of cells of different living organisms. Lipids, carbohydrates, nucleic acids and proteins are the major substances forming living organisms

Chemistry and Physics

Physics: The science that studies nature, matter, energy and forces.

Chemistry helps in creating new accurate measurement methods.

Physical Chemistry: The science that studies the structure of substances, their properties and the particles forming them.

Chemistry, Medicine and Pharmacy

Chemistry helps in the industry of medicines and understanding how hormones and enzymes work inside human body. Medicines are used to treat any disorders in them. Chemists prepare these medicines using natural substances.

Chemistry and Agriculture

Chemistry helps in:-

1- Choosing suitable soil for planting certain crops by means of "chemical analysis" which determines the ratios of soil components to know if they can satisfy the plant's needs

2- Determination of suitable fertilizers for soil to increase its production.

3- The industry of insecticides and pesticides.

Chemistry and the future

Chemistry help us discover and create new useful extraordinary substances (by means of nanotechnology) in all fields of life (Medicine, Communications, Engineering…etc)

Branches of chemistry

1- Physical chemistry

2- Biochemistry

3- Organic chemistry

4- Thermodynamic chemistry

5- Nuclear chemistry

6- Electrochemistry

7- Environmental chemistry

8- Analytical chemistry

The nature of measurement

The scientific and industrial development these days are due to the right and accurate use of measurement principles

Measurement: Comparing an unknown quantity to another one of the same kind to know its size, degree or amount

Measurement process should have 3 main points:-

1- Numerical value: By which we describe the measured quantity

2- Suitable measuring unit: A magnitude of a certain physical quantity approved by a law and used as a standard to measure the actual magnitude of this physical quantity.

3- Certain error ratio: due to an error in the used device, its use conditions, or an error caused by the user.

The importance of measurement

1- Used to know the kind and concentration of the substances we use.

2- It's essential for protection and control.

3- The evaluation of situations and proposing solutions for expected errors.

Measurement system and its units

After the industrial development during the industrial revolution (in Europe), the traditional measuring units became insufficient for measurement; which highlighted the need of unifying measurement system internationally

Old measurement systems: the French system, then the English system, and finally the international system of measuring units (IS)(used till now)

Some measuring units:-

Symbol	Unit	Measured quantity
m	Meter	Length or distance
kg	Kilogram	Mass
s	Second	Time
K	Kelvin	Temperature
A	Ampere	Intensity
Mol.	Mole	Quantity of matter
Cd	Candela	Luminosity
Coul.	Coulomb	Quantity of electricity

Some units were derived form these mentioned units such as:-

*Joule (J) kg.m2.S-2 : used for measuring the amount of heat, work and energy

* Degree Celsius (°C) : used for measuring temperature ( 0 C = 273 Kelvin)

Requirements of a chemical laboratory

1- Suitable security precautions

2- Water and heat sources

3- Places for keeping chemical substances, tools and devices

Examples of some chemical tools

The sensitive balance:-